This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-217150, filed Jul. 30, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a disk drive with head loading/unloading mechanism and more specifically to the structure of a head parking member that withdraws heads from disks at unload time.
In recent years, various technologies have been developed to meet high recording density requirements of hard disk drives (HDD). Among these is a head loading/unloading mechanism (also referred to as a head parking member load mechanism) for loading a head toward a disk and unloading (or retracting) it from the disk.
The mechanism is intended to, at the termination of a read/write operation, unload the head from the disk and withdraw it to a member, called a head parking member, which is placed outside the disk. At the start of an read/write operation, the mechanism moves the head from the head parking member over the disk and then loads it toward the disk. Here, the head is a flying head that comprises a slider on which a read head (MR head) and a write head are mounted and floats just over the disk surface for reading from and writing to the disk.
Such a mechanism allows the elimination of contact between the head and the disk surface at unload time because the head is withdrawn to the head parking member. Therefore, disks used are allowed to have a very smooth surface, thus allowing the head-to-disk spacing to be reduced. This leads to an increase in data recording density.
In general, in HDDS that use the head loading/unloading mechanism, the aforementioned ram is mounted in proximity to the circumference of the disk that is driven to spin by a spindle motor. In the HDDs, the heads are mounted on a rotary type of actuator driven by a voice coil motor (VCM). When the actuator is driven, the head moves radially across the surface of the spinning disk while floating above the disk surface. To the actuator is attached a unloading bar-like member called a tab. Specifically, the tab is attached to the end of a suspension which is a component of the actuator. The suspension is a plate spring member on which the heads are mounted.
The unload operation is withdrawing the heads positioned over the disk to the head parking member by moving the actuator toward the outside of the disk when a command is given to stop disk rotation (or when the power is turned off). The unload operation is also called the retract operation. The load operation is moving the heads placed in the unloaded state over the disk by moving the actuator toward the inside of the disk.
In the unload operation, when the actuator approaches the head parking member, the tab slides on the unload surface of the tab and reaches the predetermined stop position (parking area). That is to say, the heads are placed in the withdrawn state when the tab is at rest in the parking area (recessed area).
FIGS. 8A and 8B each show a state, as viewed from the disk side, where tabs 131 are brought into contact with unload surfaces 142 of a head parking member 14. With the structure of the head parking member 14 shown in FIG. 18A, in the event that an external shock is applied to the HDD body after the heads are withdrawn from the disk, the tabs 131 can jump from the unload surfaces 142.
In that event, the suspension may also vibrate and, in the worst case, the heads mounted on the suspension may become damaged. To prevent the tabs at rest on the unload surfaces from jumping, such a head parking member as shown in FIG. 8B has been developed which has height-limiting members 140 called limiters.
An unload operation when the head parking member 14 provided with such limiters is used will be described with reference to FIG. 9.
When the head positioned over the disk has come to the head parking member 14, the tab 131 slides on the unload surface 142 in the direction of an arrow 90 and comes to rest in the parking area (recessed area) 141 on the unload surface. In this case, the design is such that, when the actuator hits a stopper made of rubber to stop, the tab 131 comes to rest in the parking area 141.
To prevent the heads from becoming damaged due to a shock resulting from the actuator hitting the stopper, the rubber stopper is deformed to absorb the shock. For this reason, the tab 131 will move in the direction of an arrow 92 up to the back of the parking area 141 (overshoot position). And now, the resiliency of the stopper will push back the tab in the direction of an arrow 91 (the load direction), namely, in the direction of the disk 11.
As stated above, the use of a head parking member having limiting members allows the up and down movements of the tabs at rest in the parking areas to be suppressed. In the actual unload operations the tab moves on the unload surface on opposite sides of the parking area before it comes to rest in that area.
The parking area 141 is shaped in a recessed form and hence has slant surfaces that are continuous with the unload surface. Therefore, as shown in FIG. 5, the slant surfaces act like a kind of ski jump when the tab passes past the parking area, causing the tab to jump up or down. There is no limiter before and behind the parking area. As a result, such movements of the tab cannot be suppressed and, in the worst case, the heads may become damaged.
It is an object of the present invention to provide a disk drive with head loading/unloading mechanism which permits the unload-time vertical movement of an unloading tab attached to the end of an actuator having a head mounted on it to be restricted and thus prevents the head from becoming damaged by unwanted shock.
The present invention relates to the structure of a head parking member for stabilizing the state of the head at unload time in a disk drive having a head loading/unloading mechanism. Specifically, the inventive head parking member is provided outside a disk and has an unload surface on which the unloading tab slides as the actuator moves at unload time. The unloading tab is attached to the end of a suspension attached to the actuator. The suspension supports the head. The unload surface is formed with a parking area in the form of a recessed area having slant surfaces continuous with the unload surface. The parking area is a place where the unloading tab comes to rest.
Further, the head parking member is provided with a limiting member for restricting the vertical movement of the unloading tab which is moving or at rest in a given portion of the unload surface containing the parking area. Specifically, the limiting member is formed in such a way as to cover that given portion of the unload surface and be intersected by an extension of a slant surface of the parking area and is therefore permitted to restrict the movement of the unloading tab in the vertical direction with respect to the unload surface.
In the disk drive using the head parking member thus constructed, when the disk stops rotating (or the power is turned off), an unload operation is carried out to move the actuator in the direction of the ram. That is, a retract operation of withdrawing the head to the ram is carried out. When the actuator has arrived at the head parking member, the unloading tab slides on the unload surface and reaches the parking area. When the actuator stops moving, the unloading tab comes to rest in the parking area or on a portion of the unload surface before or behind the parking area. When a shock is externally applied to the disk drive while the unloading tab is at rest or moving in the given portion of the unload surface containing the parking area, the tab may jump from the unload surface. when the tab moves past the parking area, the slant surfaces act like a ski jump, causing the tab to jump upward.
In the inventive head parking member, the limiting member is formed to include not only an area that is opposed to the parking area but also an extended area that is intersected by an extension of at least one of the slant surfaces of the parking area. For this reason, the limiting member can successfully restrict the unwanted movement of the unloading tab such as jumping or vibration. Therefore, the head placed in the unloaded state can be stabilized and prevented from being damaged by unwanted shock.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.